Subjects will be admitted to the GCRC within the first 3 days after the onset of menses, or at random in amenorrhcic subjects. After an overnight fast, they will undergo 24 hours of q 10 minute blood sampling (2-3 cc per sample) for LH and insulin levels. Serum pools will be tested for SFH and sex steroids. During this stay, meals will be standardized at 0830, 1200, 1500, 1800, and 2230 hrs., with calories adjusted to maintain body weight. At the termination of blood sampling, diazoxide 100 mg po q 8 hr will be initiated for 3 days. They will be readmitted on the fifth day after an overnight fast for repeat sampling under the identical protocol. Analysis: Paired t-testing within and unpaired t-testing between groups.